1. Field of Invention
The present invention relates to a solid electrolytic capacitor, and more particularly to a solid electrolytic capacitor that has a simple structure and can be assembled quickly at a low cost.
2. Description of the Related Art
With reference to FIG. 8, a conventional aluminum electrolytic capacitor has a capacitance and comprises an aluminum housing (40), a capacitor element (50) and a seal rubber (60). The aluminum housing (40) has an open bottom and an inner chamber (41). The capacitor element (50) is mounted in the inner chamber (41) and has a body (51) and two leads (52). The body (51) is coiled and comprises an anode foil, a cathode foil and two separators. The separators are mounted between the anode foil and the cathode foil to separate the anode foil and the cathode foil. The leads (52) connect respectively to the anode foil and the cathode foil. The seal rubber (60) seals the open bottom and has two holes (61). The holes (61) are defined through the seal rubber (60) and allow the leads (52) to extend through the holes (61). The seal rubber (60) and the capacitor element (50) occupy the inner chamber (41).
However, the seal rubber (60) occupies almost one-third inner chamber (41). If the capacitance is required to increase, the dimension (either a diameter or a height) of the aluminum housing (40) will become larger. For example, when the height of the aluminum housing (40) is limited and can not be changed, the diameter of the aluminum housing (40) will be enlarged. On the contrary, when the diameter of the aluminum housing (40) is limited and can not be changed, the height of the aluminum housing (40) will be increased. Meanwhile, a thickness of the seal rubber (60) must be increased, so the inner chamber (41) cannot be fully utilized. Therefore, a dimension of the capacitor element (50) and a capacitance of the conventional aluminum electrolytic capacitor are limited. Furthermore, when the capacitor element (50) undergoes a soaking procedure, each body (51) of the capacitor element (50) is immersed in a liquid mixture with monomers, an oxidizing agent and other additives in a container. However, the liquid mixture is easy to be cured, so residue of the liquid mixture in the container is wasted. Further, cracks occur easily between the leads (52) and the body (51) when soaking the capacitor element (50). Additionally, because the leads (52) extend through the holes (61) of the seal rubber (60) without fastening to the seal rubber (60), cracks may also occur between the leads (52) and the body (51) when soaking the capacitor element (50) during the period of conveying the aluminum.
As technology progressing, electrolytic capacitors are required small and high capacitance to fit smaller and more delicate electronic devices, such as laptops. Accordingly, a plastic-housing aluminum electrolytic capacitor has been developed. The plastic-housing aluminum electrolytic capacitor has a capacitance and comprises a housing assembly and a capacitor element. The housing assembly is made of plastic and has a body, a base and a cover. The body has a partition. The partition has two through holes and is mounted transversely in the body to divide the body into an upper chamber and a lower chamber. The upper chamber is larger than the lower chamber. The base is flaky, seals the lower chamber and has a bottom, two holes and two grooves. The holes correspond to the through holes. The grooves are formed in the bottom of the base and communicate respectively with the holes. The cover is flaky and seals the upper chamber. The capacitor element is the same as the capacitor element of said aluminum electrolytic capacitor and is mounted in the upper chamber of the body. The leads extend from the through holes in the partition and the holes in the base. After the leads extend the through holes in the partition, the lower chamber is filled with epoxy resin to fasten the leads. Further, after the leads extending from the holes in the base, the leads are bent in opposite directions and are respectively mounted in the grooves.
Because the cover is thin, the upper chamber can be fully utilized. Thus, when the capacitances of the aluminum electrolytic capacitor and the plastic-housing aluminum electrolytic capacitor are the same, the plastic-housing aluminum electrolytic capacitor is smaller than the aluminum electrolytic capacitor.
However, the conventional plastic-housing aluminum electrolytic capacitor has a complex structure and has to use a lot of epoxy resin in the lower chamber, so to assemble the plastic-housing aluminum electrolytic capacitor takes a lot of time. Furthermore, the leads are mounted in the grooves and a top of each lead abuts the groove, so when the conventional plastic-housing aluminum electrolytic capacitor is soldered to a print circuit board (PCB), solder (such as tin) cannot mounted on the top of each lead. Thus, the conventional plastic-housing aluminum electrolytic capacitor cannot be mounted securely on the PCB.
To overcome the shortcomings, the present invention provides a solid electrolytic capacitor to mitigate or obviate the aforementioned problems.